Ongoing Projetcs

This research focuses on the design of a “metabarrier” capable to convert the Rayleigh waves at the seismic scale into shear bulk waves that leave the free surface and dissipate into the half space. Compared to other available strategies the metabarrier avoids rerouting the seismic energy at the soil surface that can lead to harming surrounding areas. In addition, not requiring an intervention on the target structure/infrastructure it can be suitable for monumental buildings as well for those strategic buildings which do not allow operative shut down for seismic retrofitting purposes. The “metabarrier” is built by buring at the ground surface resonators, which are in dimension sub-wavelentgh, that can be designed to shield from Rayleigh motion in the 1-10 Hz frequency range.

Engineered metabarrier for reducing vulnerability of structures and infrastructures from seismic Rayleigh waves

In this research a method for impact location in plate-like structures based on a dispersion compensation procedure of guided waves is under development. Procedures based on dispersion compensation are usually applied to active monitoring techniques, as they require the knowledge of the time of impact to effectively compensate the guided waves dispersive behaviour. Unfortunately, this knowledge is not given in passive monitoring techniques. Despite this limit, the idea is to show how dispersion compensation procedure can be used to remove in the group delay of the acquired signals the dependency on the travelled distance. By comparing the signals related to the same event acquired at different sensors the difference in travelled distances can be determined and thus used to locate  the wave source via hyperbolic positioning.

Hyperbolic defect localization in plates via signal processing of guided waves

In this work the dispersive pattern of guided waves in a human tibia is obtained by means of a semi-analytical finite element (SAFE) formulation. The dispersion curves are computed for the elastic cortical bone only. Next, the research aims at showing the excitability of the existing dispersive waves for different forcing function generally applied by medical devices. These results can be exploited in in-vitro testing of bones and can support the research on non-invasive techniques based on stress waves for osteoporosis detection and monitoring of long bones (radius, tibia, femur).

Assessment of human long bones by means of ultrasonic guided waves

Seismic metabarrier

Experimental set-up for source location

Human tibiae: (a) image, (b) cross-section, (c) SAFE mesh

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Pipe networks for both water and oil distribution suffer the formation of blockages. The blockages lower the efficiency and reliability of pipe systems, with negative economic impacts, loss of services and environmental risks. The current work focuses on a non-invasive methodology for blockages detection in pipe networks. The procedure exploits steady-state measurements of pressures and flows, a pipe network simulator and an optimization scheme based on Genetic Algorithms (GAs). The blockages are identified upon minimizing via GAs the discrepancy between the measured and the simulated data. The approach is presented conceptually, coded in a software tool and tested on a mixed branched-looped network carriyng crude oil.

Structural identification of blockages in pipe networks via steady-state measurements and Genetic Algorithms

(a) Pipe network; (b) blockages identification

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